In the past, stationary cycling machines (indoor exercise bike) and stationary running machines (treadmill) have been well known as exercise assist devices for allowing a user to voluntarily train leg muscles. On the other hand, as another exercise assist devices for providing a passive exercise to the user without the user's voluntary action, horse-riding exercise machines (e.g., Japanese Patent Publication [kokai] No. 11-155836) have been proposed.
When using the indoor exercise bike or the treadmill, there is a case that knee flexion and extension exercises are excessively provided, or a load larger than the user's own weight is applied to the knee joint. However, these are not appropriate for the user having knee pain. On the other hand, when using the conventional horse-riding exercise machines, the load applied to the knee joint is relatively small because the user sits on a seat during the exercise. However, since their purpose is to cause a muscle contraction mainly at the trunk of the body such as a lumbar portion of back, it is not necessarily enough to effectively cause leg muscle contraction.
By the way, to prevent lifestyle-related diseases that tend to rapidly increase in recent years, it is effective to reduce body fat by aerobic exercise. In addition, when sugar metabolism is enhanced by actively causing the muscle contraction to improve insulin sensitivity, it contributes to prevent the lifestyle-related diseases. To enhance the sugar metabolism by the muscle contraction, it is effective to cause the muscle contraction at a femoral region having large volume muscles. On the other hand, since diabetic patients often have knee pain, they cannot perform exercises such as squat exercise for effectively causing the muscle contraction at the femoral region. In addition, even when they perform a light exercise such as walking, there is a potential for causing clinical deterioration or an increase in knee pain. Thus, the persons who cannot perform the exercises have strong desire to exercise.
Under the circumstances, it is expected to develop equipment for efficiently training leg muscles, while minimizing the load applied to the knee.